Mercury safety switch



May 30, 1950 s. R. MATTHEWS En' A1. 2,509,514

MERCURY SAFETY SWITCH Patented May 30, 1950 :MERCURY sAFE'rY SWITCH iStanleyfR. Matthews and Thomas J. Darlington,A AWinston'Saleni, N. G;

2V Claims.

The invention, relatesto 4mercury switches and :more: particularly to.amercury type ,switch-which is adapted tohezapplied to a-roadvvehicle.

,Thecmain objectLof theliinvention is to provide a mercury .or :liquidtype A.Switch comprising two half members which are adapted to be boltedtogether, the half members embodying electrical :.terminals, theterminals communicating .-with a cavity which is normally lled with,orcontains mercury, whereby contact islmadevbetween thel respectiveterminals.

Another object of the invention is to provide a vswitch of atypement-ionedfwhieh, in=thefevent that the -switchV isturnedorf-tilted, the-mercury Willleave'cthe 4cavity-and break'fthecontact'betweenthe respectiveterminals.

Another object-of the-invention is to so fasten the. inner surfaces ofthe respective plates of the `switch whereby, when the. switch isonceturned andthe mercury leavesgcthe cavity it cannot again be returnedto'the cavity other'thanbyfmanual means.

The switch is particularly adapted for use on road vehicles andespecially trucks or tractors which, in the case of an accident or theoverturning of the vehicle the entire electrical system of the vehiclewill be disrupted and connection cannot again be made other than .bymanual operation.

The invention is illustrated in the accompanying drawings in which:

Fig. l is a top plan view of the switch showing one terminal thereofbeing connected to a battery post and the other to a terminalcommunicating with the electrical system;

Fig. 2 is a side elevation;

Fig. 3 is an end view looking at the switch from the right hand side;

Fig. 4 is an inside view of one of the halves of the switch;

Fig. 5 is an inside View of the other half of the switch, and

Fig. 6 is a section through the switch.

Referring more specifically to the drawing in which like numeralsindicate similar parts throughout the various views the switch is showngenerally at 6 and comprises two members I and 8, made entirely of aninsulating material such as fiber, the member 1 having a flangedterminal 9 fastened thereto as by bolts Ill and terminating in a clampportion II, said clamp portion being adapted to be attached to aterminal post I2 of a battery I3. The other half of the switch 8 hasattached thereto a anged portion I4 terminating in a member I5 which isadapted to be engaged by l closedgasfby screwS. Y cor" trap 22communicateswith-'the main lopening .l2 a clamp I6 of a cableterminal'II'l. As will be seen the respective terminals II and AI5 areheld in closed relation as'bythe' bolts Iand the nutsIQthreaded'thereon. Referring `speci'iically to Figure 4 the plate orportiorrlhas a mercury cavity "2t, the samehaving c onnected'theretospillways 2I, lspillways"leading to-and cooperating with a trap portion22. 'Figure 5 discloses 'theinner "construction of fthe portion'il oftheswitch -the -same embodying ajrecessed or mercury-cavity-*23 andrecesses `-2t. Memberc furtherhasat the uppermost end a jjii`lljopeningland -passage #25 Atlitslower side the' race 21' closed by-screWEE-.`'Iheerespective 4terminals 9 and Y I 4 f have -rubber or likefwashersl2 9-` spaced therebetweenat-thateportioiy where they joinv the -sideofthe cas-ing to prevent leakageA-of-thevmercury.

-Inits assembled condition -itwill readily-@beseen that the -recesses201andfi23-arei inl alignmentaand that the passages 24 permit a passagewayto the spillways 2l in the event or during the turning or inversion ofthe switch, whereby mercury or other liquid will run through thepassages into the trap or waste 22.

In the operation of the switch the same is normally placed in connectionwith one post of a battery at one side and to the electric cable at theother side, and in its normal position the recesses 23--23 are normallylled with mercury or the like, so that when the switch is in its uprightposition as shown in Figures l and 2 the mercury is trapped in therecesses and thereby it makes contact between the terminals El and i4.In the event that the vehicle to which the switch is attached isoverturned the mercury passes from the recesses through the spillways 2iinto the trap chamber 22. Once the mercury is in this trap chamber itcannot in any way be returned to its former position in the recesses25g-23, even though the vehicle should turn over several times and rightitself, the mercury would still be trapped in the raceway 22. Underthese conditions in order to make electrical contact and resume orcomplete the electrical system it would be necessary to withdraw thedrain plug 23 and drain the mercury out, after which, the plug could bereplaced and the mercury inserted through the passage 25 upon removingof the screw 26.

It will thus be seen that we have devised a very advantageous switch,mainly because, in the event that the same is once turned the liquidcannot return to make the necessary electrical contact until the same ismanually done. Thus in the event of an accident it would be impossiblefor an automobile or other vehicle to be in an accident and turn overand then right itself and automatically have the electrical systemreconnected. Thus it will readily be seen that such a switch is anabsolute precaution against the possibility of re in the event that anautomobile is turned over because the entire electrical system isdisconnected and therefore there can be no sparking which is a mainsource of lire hazard when a vehicle is overturned.

The invention is not limited to the exact construction shown but may bevaried within the scope of the following claims.

yWe claim:

1. A safety mercury type switch comprising in combination two terminalmembers and a body of insulating material, said body member consistingof two half members, each half member having a central boretherethrough, said bores formt disposed spillways communicating with thetrap Vchamber at their outer ends and having their inner ends incommunication with the mercury recess, said half member further having aradially disposed lling passage extending inwardly from the outer edgeof the member and communicating at its inner end with the mercury recessand a, mercury drain passage extending through the lower wall of thehalf member and opening in the annular recess.

2. A safety mercury switch comprising in combination two terminalmembers and a body member of insulating material, said body memberconsisting of two half members, one of each of the terminals connectedwith the outer face portion of each half member, each of the halfmembers having a. recess bored through their center portions and adaptedto align when the half members are placed face to face and thereby forma mercury recess, the terminal members having portions overlying themercury recess, the inner face part of one of the half members havingformed therein an annular trap channel and spaced apart spillways incommunication at their outer ends with the annular trap channel andradiating inwardly and communicating at their inner ends with themercury recess, a mercury drain opening extending through a wall of the.half members, and a mercury refill opening extending laterally throughthe wall of the half member and terminating at its inner end incommunication with the mercury recess, and bolt and nut means extendingthrough the respective half members and terminal members to hold theswitch in assembled relation.

STANLEY R. MATTHEWS. THOMAS J. DARLINGTON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,740,895 Kilgour Dec. 24, 19291,834,833 Ford Dec. 1, 1931 2,201,754 Worth May 21, 1940 2,417,993Porter Mar. 25, 1947 FOREIGN PATENTS Number Country Date 382,423 GreatBritain Oct. 27, 1932 387,509 Great Britain Feb. 8, 1932

